update stacker to 0.1.9 to unbreak build on OpenBSD
the version 0.1.8 of stacker (what is currently pinned in Cargo.lock) doesn't build on OpenBSD (see https://github.com/rust-lang/stacker/pull/34).
update the version to 0.1.9
Prevent compiler stack overflow for deeply recursive code
I was unable to write a test that
1. runs in under 1s
2. overflows on my machine without this patch
The following reproduces the issue, but I don't think it's sensible to include a test that takes 30s to compile. We can now easily squash newly appearing overflows by the strategic insertion of calls to `ensure_sufficient_stack`.
```rust
// compile-pass
#![recursion_limit="1000000"]
macro_rules! chain {
(EE $e:expr) => {$e.sin()};
(RECURSE $i:ident $e:expr) => {chain!($i chain!($i chain!($i chain!($i $e))))};
(Z $e:expr) => {chain!(RECURSE EE $e)};
(Y $e:expr) => {chain!(RECURSE Z $e)};
(X $e:expr) => {chain!(RECURSE Y $e)};
(A $e:expr) => {chain!(RECURSE X $e)};
(B $e:expr) => {chain!(RECURSE A $e)};
(C $e:expr) => {chain!(RECURSE B $e)};
// causes overflow on x86_64 linux
// less than 1 second until overflow on test machine
// after overflow has been fixed, takes 30s to compile :/
(D $e:expr) => {chain!(RECURSE C $e)};
(E $e:expr) => {chain!(RECURSE D $e)};
(F $e:expr) => {chain!(RECURSE E $e)};
// more than 10 seconds
(G $e:expr) => {chain!(RECURSE F $e)};
(H $e:expr) => {chain!(RECURSE G $e)};
(I $e:expr) => {chain!(RECURSE H $e)};
(J $e:expr) => {chain!(RECURSE I $e)};
(K $e:expr) => {chain!(RECURSE J $e)};
(L $e:expr) => {chain!(RECURSE L $e)};
}
fn main() {
let x = chain!(D 42.0_f32);
}
```
fixes#55471fixes#41884fixes#40161fixes#34844fixes#32594
cc @alexcrichton @rust-lang/compiler
I looked at all code that checks the recursion limit and inserted stack growth calls where appropriate.
perf: Unify the undo log of all snapshot types
Extracted from #69218 and extended to all the current snapshot types.
Since snapshotting is such a frequent action in the compiler and many of the scopes execute so little work, the act of creating the snapshot and rolling back empty/small snapshots end up showing in perf. By unifying all the logs into one the creation of snapshots becomes significantly cheaper at the cost of some complexity when combining the log with the specific data structures that are being mutated.
Depends on https://github.com/rust-lang-nursery/ena/pull/29
In addition to fixing the toolstate, this also changes the default
compilation model to the out-of-process one, which should hopefully
target considerable memory usage for long-running instances of the RLS.
By merging the undo_log of all structures part of the snapshot the cost
of creating a snapshot becomes much cheaper. Since snapshots with no or
few changes are so frequent this ends up mattering more than the slight
overhead of dispatching on the variants that map to each field.
Implement `confusable_idents` lint.
This collects all identifier symbols into `ParseSession` and examines them within the non-ascii-idents lint.
The skeleton generation part needs to be added to `unicode-security` crate. Will update this PR when the crate is updated.
r? @petrochenkov
EDIT: also included the `concat_idents` part.
We anticipate this to have uses in all sorts of crates and keeping it in
`rustc_data_structures` enables access to it from more locations without
necessarily pulling in the large `librustc` crate.
Miri: port error backtraces to std::backtrace
No need to pull in an external dependency if libstd already includes this feature (using the same dependency internally, but... still).
r? @oli-obk
Have the per-query caches store the results on arenas
This PR leverages the cache for each query to serve as storage area for the query results.
It introduces a new cache `ArenaCache`, which moves the result to an arena,
and only stores the reference in the hash map.
This allows to remove a sizeable part of the usage of the global `TyCtxt` arena.
I only migrated queries that already used arenas before.
Update backtrace-sys
Diff:
- Don't look for old RUSTC_DEBUGINFO vars (rust-lang/backtrace-rs#313)
This fixes an issue of libbacktrace never being built with debuginfo.
r? @Mark-Simulacrum
cc @alexcrichton
Move `{Free,}RegionRelations` and `FreeRegionMap` to `rustc_infer`
...and out of `rustc_middle`. This is to further #65031, albeit in a very minor way
r? @Mark-Simulacrum
Detect mistyped associated consts in `Instance::resolve`.
*Based on #71049 to prevent redundant/misleading downstream errors.*
Fixes#70942 by refusing to resolve an associated `const` if it doesn't have the same type in the `impl` that it does in the `trait` (which we assume had errored, and `delay_span_bug` guards against bugs).
Deprecate the asm! macro in favor of llvm_asm!
Since we will be changing the syntax of `asm!` soon, deprecate it and encourage people to use `llvm_asm!` instead (which preserves the old syntax). This will avoid breakage when `asm!` is changed.
RFC: https://github.com/rust-lang/rfcs/pull/2843
Rollup of 6 pull requests
Successful merges:
- #69903 (Do not ICE in the face of invalid enum discriminant)
- #70354 (Update RELEASES.md for 1.43.0)
- #70774 (End cleanup on rustdoc-js tools)
- #70990 (Improve rustdoc source code a bit)
- #71145 (Add illumos triple)
- #71166 (Clean up E0518 explanation)
Failed merges:
r? @ghost
submodules: update clippy from af5940b7 to d236b30a
Changes:
````
rustup https://github.com/rust-lang/rust/pull/70643
Explain panic on `E0463` in integration tests
Temporarily disable rustfmt integration test
Cleanup: Use rustc's is_proc_macro_attr
Cleanup: Use our `sym!` macro more
Fixes#5405: redundant clone false positive with arrays
update lints
verbose_bit_mask: fix bit mask used in docs
Update documentation for new_ret_no_self
````
Fixes#71114
Changes:
````
Rename dummy_hir_id -> parent_hir_id
rustup https://github.com/rust-lang/rust/pull/71116
Change default many single char names threshold
Better precedence case management + more tests
Use only check_expr with parent expr and precedence
Check for Deref trait impl + add fixed version
Report using stmts and expr + tests
Global rework + fix imports
Working basic dereference clip
Add test for zero single char names
Make the single char threshold strict inequality
large_enum_variant: Report sizes of variants
Refactor: Use rustc's `match_def_path`
deps: bump compiletest-rs from 0.4 to 0.5
rustup https://github.com/rust-lang/rust/pull/70643
Explain panic on `E0463` in integration tests
Temporarily disable rustfmt integration test
result_map_unit_fn: Fix incorrect UI tests
Cleanup: Use rustc's is_proc_macro_attr
Cleanup: Use our `sym!` macro more
Fixes#5405: redundant clone false positive with arrays
Disallow bit-shifting in `integer_arithmetic` lint
update lints
cargo dev fmt
Make use of Option/Result diagnostic items
Make use of some existing diagnostic items
Say that diagnostic items are preferred over paths
verbose_bit_mask: fix bit mask used in docs
Update documentation for new_ret_no_self
Update doc generation script
Add lint on large const arrays
Make the epsilon note spanless
Split check_fn function
Indicate when arrays are compared in error message
Make epsilon note spanless when comparing arrays
Add float cmp const tests for arrays
Add float cmp tests for arrays
Handle constant arrays with single value
Don't show comparison suggestion for arrays
Allow for const arrays of zeros
Handle evaluating constant index expression
Add handling of float arrays to miri_to_const
Update stderr of float_cmp test
Update field names in is_float
Add tests for float in array comparison
Add lint when comparing floats in an array
````
Fixes#71114
update openssl-src to 111.8.1+1.1.1f
This update includes a fix for alexcrichton/openssl-src-rs#52 which allows Cargo to build correctly on Solaris/illumos.
add basic IP support in HermitCore
- add initial version to support sockets
- use TcpStream as test case
- HermitCore uses smoltcp as IP stack for pure Rust applications
- further functionalities (e.g. UDP support) will be added step by step
- in principle, the current PR is a revision of #69404
Polonius: update to 0.12.1, fix more move errors false positives, update test expectations
This PR:
- updates `polonius-engine` to version 0.12.1 to fix some move errors false positives
- fixes a fact generation mistake creating the other move errors false positives
- updates the test expectations for the polonius compare-mode so that all (minus the 2 OOMs) ui tests pass again (matching the [analysis doc](https://hackmd.io/CjYB0fs4Q9CweyeTdKWyEg?view) starting at case 34)
In my opinion, this is safe to rollup.
r? @nikomatsakis
submodules: update clippy from 1ff81c1b to 70b93aab
Changes:
````
remove redundant import
rustup https://github.com/rust-lang/rust/pull/68404
rustup https://github.com/rust-lang/rust/pull/69644
rustup https://github.com/rust-lang/rust/pull/70344
Move verbose_file_reads to restriction
move redundant_pub_crate to nursery
readme: explain how to run only a single lint on a codebase
Remove dependency on `matches` crate
Move useless_transmute to nursery
nursery group -> style
Update for PR feedback
Auto merge of #5314 - ehuss:remove-git2, r=flip1995
Lint for `pub(crate)` items that are not crate visible due to the visibility of the module that contains them
````
Fixes#70456
Changes:
````
remove redundant import
rustup https://github.com/rust-lang/rust/pull/68404
rustup https://github.com/rust-lang/rust/pull/69644
rustup https://github.com/rust-lang/rust/pull/70344
Move verbose_file_reads to restriction
move redundant_pub_crate to nursery
readme: explain how to run only a single lint on a codebase
Remove dependency on `matches` crate
Move useless_transmute to nursery
nursery group -> style
Update for PR feedback
Auto merge of #5314 - ehuss:remove-git2, r=flip1995
Lint for `pub(crate)` items that are not crate visible due to the visibility of the module that contains them
````
Fixes#70456
Move the query system to a dedicated crate
The query system `rustc::ty::query` is split out into the `rustc_query_system` crate.
Some commits are unformatted, to ease rebasing.
Based on #67761 and #69910.
r? @Zoxc
Decouple `rustc_hir::print` into `rustc_hir_pretty`
High level summary:
- The HIR pretty printer, `rustc_hir::print` is moved into a new crate `rustc_hir_pretty`.
- `rustc_ast_pretty` and `rustc_errors` are dropped as `rustc_hir` dependencies.
- The dependence on HIR pretty is generally reduced, leaving `rustc_save_analysis`, `rustdoc`, `rustc_metadata`, and `rustc_driver` as the remaining clients.
The main goal here is to reduce `rustc_hir`'s dependencies and its size such that it can start and finish earlier, thereby working towards https://github.com/rust-lang/rust/issues/65031.
r? @Zoxc
Update backtrace crate to 0.3.46
* Support line-tables-only when using libbacktrace
* Update libbacktrace to latest master
* Define HAVE_KERN_PROC on FreeBSD to fixrust-lang/rust#54434
- add initial version to support sockets
- use TcpStream as test case
- HermitCore uses smoltcp as IP stack for pure Rust applications
- further functionalities (e.g. UDP support) will be added step by step
tidy: Better license checks.
This implements some improvements to the license checks in tidy:
* Use `cargo_metadata` instead of parsing vendored crates. This allows license checks to run without vendoring enabled, and allows the checks to run on PR builds.
* Check for stale entries.
* Check that the licenses for exceptions are what we think they are.
* Verify exceptions do not leak into the runtime.
Closes#62618Closes#62619Closes#63238 (I think)
There are some substantive changes here. The follow licenses have changed from the original comments:
* openssl BSD+advertising clause to Apache-2.0
* pest MPL2 to MIT/Apache-2.0
* smallvec MPL2 to MIT/Apache-2.0
* clippy lints MPL2 to MIT OR Apache-2.0
Remove some imports to the rustc crate
- When we have `NestedVisitorMap::None`, we use `type Map = dyn intravisit::Map<'v>;` instead of the actual map. This doesn't actually result in dynamic dispatch (in the future we may want to use an associated type default to simplify the code).
- Use `rustc_session::` imports instead of `rustc::{session, lint}`.
r? @Zoxc
Changes:
````
rustup https://github.com/rust-lang/rust/pull/69738
rustup https://github.com/rust-lang/rust/pull/68944
Make use of `or_patterns` feature
rustup https://github.com/rust-lang/rust/pull/69589/
Rustup to rust-lang/rust#69076
Don't convert Path to lossy str
Use `into_path`
Use pattern matching instead of manually checking condition
Fix typo
Remove git2 dependency.
Document that wildcard_imports doesn't warn about `use ...::prelude::*;`
Change changelog formatting
Update changelog_update doc to reflect the actual ordering of the changelog
Update CHANGELOG.md
````
Fixes#70007
Changes:
````
Rustup to rust-lang/rust#69674
Use visit_place
Check for mutation
Only fires on temporaries
Extend `redundant_clone` to the case that cloned value is not consumed
add CR feedback
Improve documentation
Use `edition:2018` flag more widely
Update tests/ui/needless_doc_main.rs
Move links to the end of each chapter on adding_lints
Move links to the end of each chapter on CONTRIBUTING
Clean-up adding_lints.md
Clean-up CONTRIBUTING.md
needless_doc_main: only check rust code
Use `node_type_opt` over `node_type`
Fix doc
Fix ICE with trivial_bounds feature
clippy_lints: readme: don't mention crates.io since it is no longer used to publish clippy.
update rust-lang.github.io to rustc-dev-guide.rust-lang.org
Improve placeholder in map_unit_fn
Fix match single binding when in a let stmt
Improve error messages for {option,result}_map_unit_fn
Mention the setup instructions in CONTRIBUTING
redundant_pattern: take binding (ref, ref mut) into account in suggestion.
check_pat: delay creation of the "normal" vec until we reach the branch where is is actually needed
deps: bump itertools 0.8 -> 0.9
add lint on File::read_to_string and File::read_to_end
transition rustc-guide to rustc-dev-guide
Rename macro_use_import -> macro_use_imports
warn on macro_use attr
Fix deploy script for tag deploys
````
Fixes#69957
Polonius: update `polonius-engine` to 0.12.0
Since @albins won't have the time to finish up #68993 for a while, I'll take care of the trivial remaining tasks (rebasing, taking care of tidy/rustfmt).
I'll r? @nikomatsakis since they're assigned to #68993, but have actually [already reviewed it pre-rebase](https://github.com/rust-lang/rust/pull/68993#issuecomment-586413089).
When CI passes: I'll notify bors and close#68993, since this PR supersedes it.
Remove experimental chalk option
As suggested by @nikomatsakis [here](https://github.com/rust-lang/rust/pull/68807#issuecomment-583339932).
The current version of chalk used by the experimental `-Zchalk` flag is [v0.9.0, which is over a year old](https://crates.io/crates/chalk-engine). Since v0.9.0, chalk has seen [a lot of further development](https://github.com/rust-lang/chalk/compare/41dfe13...master), and the intent is to eventually upgrade rustc to use a more recent chalk.
However, it will take a decent chunk of effort to upgrade the current experimental chalk support, and it is currently [blocking at least some PRs](https://github.com/rust-lang/rust/pull/68807) due to chalk:0.9.0's use of unstable features. So for the interim until the next chalk release and experimental rustc integration, we remove the chalk-specific code from rustc.
[experiment] Support linking from a .rlink file
Flag `-Z no-link` was previously introduced, which allows creating an `.rlink` file to perform compilation without linking. This change enables linking from an `.rlink` file.
Part of Issue #64191
Flag `-Z no-link` was previously introduced, which allows creating
an `.rlink` file to perform compilation without linking.
This change enables linking from an `.rlink` file.
Changes:
````
Update jobserver.
Update tar.
Emit report on error with Ztimings.
Do not run `formats_source` if `rustfmt` is not available
Fix rebuild_sub_package_then_while_package on HFS.
Remove likely brittle test.
Install rustfmt for testing in CI
Fix build-std collisions.
Fix BuildScriptOutput when a build script is run multiple times.
Fix required-features using renamed dependencies.
Fix using global options before an alias.
Update changelog for 1.42.
Bump to 0.44.0.
Log rustfmt output if it fails; also do not check that rustfmt exists
Update pretty_env_logger requirement from 0.3 to 0.4
Swap std::sync::mpsc channel with crossbeam_channel
Fix tests on Linux/MacOS
Fix typo.
Add tests
Deduplicate warnings about missing rustfmt
Log entry 2: first implementation
Refactor code
Stabilize config-profile.
Log entry 1
Format code
Remove tempdir after install
Keep existing package with git install
Use non-ephemeral workspace
Test that git install reads virtual manifest
Fix failing test
Search for root manifest with ephemeral workspaces
Support out-dir in build section of Cargo configuration file
````
Update cargo, books
## cargo
9 commits in ad3dbe10e1e654fb1f032a5dd9481d7cbaa00d65..f6449ba236db31995255ac5e4cad4ab88296a7c6
2020-01-13 21:37:15 +0000 to 2020-01-21 16:15:39 +0000
- Fix wrong directories in host_libdir. (rust-lang/cargo#7798)
- Update humantime requirement from 1.2.0 to 2.0.0 (rust-lang/cargo#7815)
- Fix doc_target test which no longer works on stable/beta. (rust-lang/cargo#7817)
- Fix some erroneous em-dashes in man pages. (rust-lang/cargo#7814)
- fix some clippy warnings (rust-lang/cargo#7808)
- Don't assume iowait always increases on Linux (rust-lang/cargo#7803)
- Add and update some doc comments. (rust-lang/cargo#7800)
- Consistently use em-dash in environment documentation page. (rust-lang/cargo#7799)
- Load credentials only when needed (rust-lang/cargo#7774)
## reference
3 commits in e1157538e86d83df0cf95d5e33bd943f80d0248f..11e893fc1357bc688418ddf1087c2b7aa25d154d
2019-12-22 13:13:14 +0100 to 2020-01-18 21:24:08 +0100
- Small improvements to types/pointer.md (rust-lang-nursery/reference#726)
- repr(transparent): mention align=1 requirement (rust-lang-nursery/reference#737)
- Elaborate on how to use an extern static correctly (rust-lang-nursery/reference#736)
## book
4 commits in 5c5cfd2e94cd42632798d9bd3d1116133e128ac9..87dd6843678575f8dda962f239d14ef4be14b352
2019-12-16 09:27:21 -0600 to 2020-01-20 15:20:40 -0500
- Fix listing numbers (rust-lang/book#2227)
- Move `async` and `await` keywords to 'Currently in Use' (rust-lang/book#2140)
- More cleanup - remove unneeded files (rust-lang/book#2213)
- Small cleanups extracted from the bigger pr i'm working on (rust-lang/book#2212)
## rust-by-example
1 commits in 1d59403cb5269c190cc52a95584ecc280345495a..1c2bd024d13f8011307e13386cf1fea2180352b5
2019-12-27 08:27:05 -0300 to 2020-01-20 12:18:36 -0300
- CamelCase -> UpperCamelCase (rust-lang/rust-by-example#1302)
## embedded-book
1 commits in 9493b7d4dc97eda439bd8780f05ad7b234cd1cd7..4d78994915af1bde9a95c04a8c27d8dca066232a
2019-12-27 20:05:00 +0000 to 2020-01-14 08:25:25 +0000
- Update .gitattributes (rust-embedded/book#221)
Optimize size/speed of Unicode datasets
The overall implementation has the same general idea as the prior approach,
which was based on a compressed trie structure, but modified to use less space
(and, coincidentally, be an overall performance improvement).
Sizes | Old | New | New/current
-- | -- | -- | --
Alphabetic | 4616 | 2982 | 64.60%
Case_Ignorable | 3144 | 2112 | 67.18%
Cased | 2376 | 934 | 39.31%
Cc | 19 | 43 | 226.32%
Grapheme_Extend | 3072 | 1734 | 56.45%
Lowercase | 2328 | 985 | 42.31%
N | 2648 | 1239 | 46.79%
Uppercase | 1978 | 934 | 47.22%
White_Space | 241 | 140 | 58.09%
| | |
Total | 20422 | 11103 | 54.37%
This table shows the size of the old and new tables in bytes. The most important
of these tables is "Grapheme_Extend", as it is present in essentially all Rust
programs due to being called from `str`'s Debug impl (`char::escape_debug`). In
a representative case given by this [blog post] for the embedded world, the
shrinking in this PR shrinks the final binary by 1,604 bytes, from 14,440 to
12,836.
The performance of these new tables, based on the (rough) benchmark of linearly
scanning the entire valid set of chars, querying for each `is_*`, is roughly
~50% better, though in some cases is either on par or slightly (3-5%) worse. In
practice, I believe the size benefits of this PR are the main concern. The new
implementation has been tested to be equivalent to the current nightly in terms
of returned values on the set of valid chars.
A (relatively) high-level explanation of the specific compression scheme used
can be found [in the generator].
This is split into three commits -- the first adds the generator which produces
the Rust code for the tables, the second adds support code for the lookup, and
the third actually swaps the current implementation out for the new one.
[blog post]: https://jamesmunns.com/blog/fmt-unreasonably-expensive/
[in the generator]: https://github.com/Mark-Simulacrum/rust/blob/unicode-tables/src/tools/unicode-table-generator/src/raw_emitter.rs
Rollup of 12 pull requests
Successful merges:
- #67784 (Reset Formatter flags on exit from pad_integral)
- #67914 (Don't run const propagation on items with inconsistent bounds)
- #68141 (use winapi for non-stdlib Windows bindings)
- #68211 (Add failing example for E0170 explanation)
- #68219 (Untangle ZST validation from integer validation and generalize it to all zsts)
- #68222 (Update the wasi-libc bundled with libstd)
- #68226 (Avoid calling tcx.hir().get() on CRATE_HIR_ID)
- #68227 (Update to a version of cmake with windows arm64 support)
- #68229 (Update iovec to a version with no winapi dependency)
- #68230 (Update libssh2-sys to a version that can build for aarch64-pc-windows…)
- #68231 (Better support for cross compilation on Windows.)
- #68233 (Update compiler_builtins with changes to fix 128 bit integer remainder for aarch64 windows.)
Failed merges:
r? @ghost
Update compiler_builtins with changes to fix 128 bit integer remainder for aarch64 windows.
I have been investigating enabling panic=unwind for aarch64-pc-windows-msvc (see #65313) and building rustc and cargo hosted on aarch64-pc-windows-msvc.
Update libssh2-sys to a version that can build for aarch64-pc-windows…
I have been investigating enabling panic=unwind for aarch64-pc-windows-msvc (see #65313) and building rustc and cargo hosted on aarch64-pc-windows-msvc.
Update iovec to a version with no winapi dependency
I have been investigating enabling panic=unwind for aarch64-pc-windows-msvc (see #65313) and building rustc and cargo hosted on aarch64-pc-windows-msvc.
Update to a version of cmake with windows arm64 support
I have been investigating enabling panic=unwind for aarch64-pc-windows-msvc (see #65313) and building rustc and cargo hosted on aarch64-pc-windows-msvc.
Split MIR building into its own crate
This moves `rustc_mir::{build, hair, lints}` to `rustc_mir_build`.
The new crate only has a `provide` function as it's public API.
Based on #67898
cc @Centril @rust-lang/compiler
r? @oli-obk
Extract `rustc_ast_passes`, move gating, & refactor linting
Based on https://github.com/rust-lang/rust/pull/67770.
This PR extracts a crate `rustc_ast_passes`:
- `ast_validation.rs`, which is contributed by `rustc_passes` (now only has HIR based passes) -- the goal here is to improve recompilation of the parser,
- `feature_gate.rs`, which is contributed by `syntax` and performs post-expansion-gating & final erroring for pre-expansion gating,
- `show_span`, which is contributed by `syntax`.
To facilitate this, we first have to also:
- Move `{leveled_}feature_err{_err}` from `syntax::feature_gate::check` into `rustc_session::parse`.
- Move `get_features` into `rustc_parse::config`, the only place it is used.
- Move some some lint datatypes and traits, e.g. `LintBuffer`, `BufferedEarlyLint`, `BuiltinLintDiagnostics`, `LintPass`, and `LintArray` into `rustc_session::lint`.
- Move all the hard-wired lint `static`s into `rustc_session::lint::builtin`.
build-std compatible sanitizer support
### Motivation
When using `-Z sanitizer=*` feature it is essential that both user code and
standard library is instrumented. Otherwise the utility of sanitizer will be
limited, or its use will be impractical like in the case of memory sanitizer.
The recently introduced cargo feature build-std makes it possible to rebuild
standard library with arbitrary rustc flags. Unfortunately, those changes alone
do not make it easy to rebuild standard library with sanitizers, since runtimes
are dependencies of std that have to be build in specific environment,
generally not available outside rustbuild process. Additionally rebuilding them
requires presence of llvm-config and compiler-rt sources.
The goal of changes proposed here is to make it possible to avoid rebuilding
sanitizer runtimes when rebuilding the std, thus making it possible to
instrument standard library for use with sanitizer with simple, although
verbose command:
```
env CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUSTFLAGS=-Zsanitizer=thread cargo test -Zbuild-std --target x86_64-unknown-linux-gnu
```
### Implementation
* Sanitizer runtimes are no long packed into crates. Instead, libraries build
from compiler-rt are used as is, after renaming them into `librusc_rt.*`.
* rustc obtains runtimes from target libdir for default sysroot, so that
they are not required in custom build sysroots created with build-std.
* The runtimes are only linked-in into executables to address issue #64629.
(in previous design it was hard to avoid linking runtimes into static
libraries produced by rustc as demonstrated by sanitizer-staticlib-link
test, which still passes despite changes made in #64780).
cc @kennytm, @japaric, @firstyear, @choller
